What sets the Democrats’ woes apart from those of the Republicans in 2006 is the gap between the party’s rhetoric and the “summer of scandal” that has marred the start of Mr. Obama’s second term. “Phony or not, the administration in recent months has had to deal with the IRS-tea party scandal; the questions surrounding the attack on the U.S. compound in Benghazi; clashes with the press over aggressive leak investigations and the seizing of press phone records; and the fallout from the leaking of widespread government surveillance and intelligence-gathering programs.

“What we’re seeing from the Obama administration is this raw abuse of power that we haven’t seen since Watergate,” Mr. Wadhams said. “I think that’s what sets this apart.”

That is not how Mrs. Pelosi views the uproar. During a May news conference on Capitol Hill, she rejected suggestions that Democrats, led by President Obama, are caught in their own culture of corruption.

“They make so much of these issues because this president is such a great president,” said Mrs. Pelosi, adding that “some of them are legitimate issues, but they should not dominate everything.”